The nucleic acid data:
IRESite Id: 331 Version: 2
Originaly submitted by: Martin Mokrejš
Reviewed by: Martin Mokrejš Last change: 2008-05-13 18:14:47
IRESite record type:
  natural_transcript
The shape of the nucleic acid molecule translated:
  linear
The quality of the mRNA/+RNA sequence:
  our_best_guess
The abbreviated name of the virus/gene coding for this mRNA/+RNA molecule:
  Hsp83
The genetic origin of this natural mRNA/+RNA:
  nuclear
The GenBankId GI:# number of exactly this mRNA/+RNA sequence:
24656565
Synonyms of the gene name:
Synonym: 143198_at
Synonym: 83
Synonym: 83K HSP
Synonym: CG1242
Synonym: DMHSP82
Synonym: E(sev)3A
Synonym: E(sina)2
Synonym: HSP82
Synonym: HSP83
Synonym: HSP90
Synonym: ORF1
Synonym: anon-WO0068693
Synonym: clone 2.53
Synonym: en(lz)3C/4C
Synonym: hsp84
Synonym: l(3)j5C2
Synonym: ms(3)08445
The mRNA/+RNA description: 
Drosophila melanogaster Heat shock protein 83 CG1242-RA (Hsp83), mRNA.
The mRNA/+RNA sequence represented in the +DNA notation:


Credibility of mRNA sequence:
  only_fragment_published_or_from_author_and_the_rest_is_a_guess
The organism containing this mRNA with IRES segment in its genome:
Drosophila melanogaster
A promoter reported in cDNA corresponding to IRES sequence:
  not tested
The total number of notable open-reading frames (ORFs):
  1
Notable Open-Reading Frames (ORFs; protein coding regions) in the mRNA/+RNA sequence:
ORF
ORF position:   1
Version: 1 Last change: 2009-09-01 21:42:25
Originaly submitted by: Martin Mokrejš Reviewed by: Martin Mokrejš
The abbreviated name of this ORF/gene:
Hsp83
The description of the protein encoded in this ORF:
Heat shock protein 83 CG1242-PA
The translational frameshift (ribosome slippage) involved:
  0
The ribosome read-through involved:
  no
The alternative forms of this protein occur by the alternative initiation of translation:
  no
The ORF absolute position (the base range includes START and STOP codons or their equivalents):
  342-2495
Remarks:
The cloned 5'-UTR by Ahmed, R. and Duncan, R.F.(2004) was not the entire 5'-UTR. Nucleotide number one
published by them is the 193rd nucleotide according to GI:24656565. The sequence gene model can be confirmed
by EST records GI:13698172, GI:13689118, GI:13684254, GI:3102337, GI:114073046 (the last EST contains also the
poly(A) region).
Citations:
Ahmed R., Duncan R. F. (2004) Translational regulation of Hsp90 mRNA. AUG-proximal 5'-untranslated region elements essential for preferential heat shock translation. J. Biol. Chem. 279(48):49919-49930
IRESs:
IRES:
Version: 2 Last change: 2008-05-13 18:14:47
Originaly submitted by: Martin Mokrejš Reviewed by: Martin Mokrejš
The IRES name:
  Hsp90
Warning: please make ires_name same as the gene_name and optionally append to it coordinates. E.g. when gene/virus name is EMCV-R use EMCV-R_-222_to_-1 or EMCV-R_1-456, etc. but not Emcv-R-... or EMCV-222_to_-1. Please keep case of letters as well. This rewards when searching through the database.
The IRES absolute position (the range includes START and STOP codons or their equivalents):
  193-341
Conclusion:
  unproved_IRES
How IRES boundaries were determined:
experimentally_determined
The sequence of IRES region aligned to its secondary structure (if available):


Remarks:
Possibility of IRES-mediated translation was tested under normal and heat-shock conditions in Drosophila
melanogaster S2 cells. If at all, IRES activity was confirmed only in the heat shock conditions while under
normal circumstances the cap-dependent translation driven by eIF4E (and sensitive to the eIF4E-BP
overexpression) is prevalent. However, authors did not state clearly there is IRES activity at all.

The rate of synthesis of Hsp90 protein (Fig. 1A) was increased by heat shock. The biggest increase was noticed
when the temperature raised from 29 to 35 °C and from 35 to 37 °C the protein synthesis decreased.

Actinomycin D treatment (Fig. 1) which blocks transcription was used to study efficiency of translation of
various Hsp mRNAs (Hsp90, Hsp70, Hsp26/28, Hsp22/23) in Drosophila S2 cells. With increasing heat shock the
amount of radiolabeled Hsp90 proteins newly translated increased whereas amounts of Hsp70, 26/28 and 22/23
proteins decreased. It has been concluded that some of 5'-UTRs mediate more efficiently translation of their
respective messages.

No bicistronic mRNA tests were employed at all, no positive control containing known IRES has been used, and
neither direct RNA transfection was performed nor T7 polymerase-based cytoplasmic transcription was used to
prove the special advantage of Hsp90 5'-UTR is due to IRES.

Overexpression of eIF4E-BP (Fig. 5) reduced the translation of Hsp90 by >95% under normal growth temperature
(22-24 °C) whereas during heat shock (36 °C, 15 min) overexpression of eIF4E-BP inhibited Hsp90 IRES
activity to ~60% only.

Authors confirmed that Drosophila eIF4E-BP is dephosphorylated during heat shock and therefore is expected to
be able to bind eIF4E (Fig. 6). These results say that it is concerned about cap-dependent translation.

In figure 8 various deletions of the incomplete 5'-UTR showed that the region 77-149 nt (269-341 region of the
complete 5'-UTR of GI:24656565 annotated here in IRESite) confers at least some translation advantage during
heat shock. But, it is unclear whether this is due to a stable secondary structure which melts during heat
shock or whether it is contributed (even in part) by IRES. In this experiment, Drosophila S2 cells were
transfected by a metalothionein promoter-driven expression plasmid MT90-FL (metallothionein-promoter ->
Hsp90 5'-UTR (193-341 of GI:24656565)-> "internally deleted" Hsp70 coding region containing only 44kDa region
of Hsp70 -> Hsp70 3'-UTR) expressing 44kDa protein (Hess and Duncan, 1996). In the legend this figure 8
authors say that translation rate equals translational efficiency which is supported by Northern analysis
(data not shown).
Citations:
Ahmed R., Duncan R. F. (2004) Translational regulation of Hsp90 mRNA. AUG-proximal 5'-untranslated region elements essential for preferential heat shock translation. J. Biol. Chem. 279(48):49919-49930
Hess M. A., Duncan R. F. (1996) Sequence and structure determinants of Drosophila Hsp70 mRNA translation: 5'UTR secondary structure specifically inhibits heat shock protein mRNA translation. Nucleic Acids Res. 24(12):2441-2449
Last change to the database: 2015-04-16 16:45:23 GMT+1